HKphooey
Senior Master
Unlike wine, beer doesn't get better with age. Once the fermentation (1st and 2nd stage) is done and the beer has been conditioned in the bottle or force carbonated in a cask beer will start to lose it's "freshness". Hence the "born on" date of one of the big breweries. My understanding is that there are certain additives to help maintain the beer at a certain level of taste. After about a month in dark bottles you can start to thell a big difference in the taste.
That is why I am sure to drink them up quickly.